This invention relates to a method of driving of a vehicle with automatic transmission.
It is known from practice that in a planetary type a conventional automatic gearbox usually contains a hydrodynamic converter with a manually switching gearbox, wherein the converter in a given operation is defined according to effective power flow inside the planetary group through the clutch and brakes, respectively. As a rule, to control the pressurization of these clutches an electronic gear driving with an electronic driving device is utilized. This control is set, for example, through electromagnetic and electrohydraulic position links of hydraulic pressure, which is set, for instance, next to multi-plate clutch rest. This filling pressure of the clutch is isolated by the known gear driving of a state outside a gear change depending on gearbox input factor and, correspondingly, motor factor and a certain operation step as a characteristic curve in an electronic driving device.
According to the notion of clutch pressure-characteristic curve, in practice, a minimum coefficient of friction was calculated according to component tolerance and eventual incoming damage to the clutch, which was taken into consideration while calculating the necessary pressure in the clutch according to the characteristic curve. In order to avoid the gearbox damage, the notion of characteristic curve as the xe2x80x9cweakest, i.e., the greatest required pressurization, in a particular/respective gear-switching clutch was applied to the clutch pressure.
As a minimum transmission capability of the clutch provides for a possible decrease of clutch friction coefficient and respectively for brakes or insufficient factor interface of the engine, the minimum transmission is applied to distributed characteristic curve of clutch pressure with a respectively strong safety in an electric driving gear. Also with a properly functioning system concerning disadvantages, very high-pressure reserves must become available which general lead to deterioration of the gearbox efficiency.
In spite of such, strong safety default for the characteristic curve of clutch pressure, it has shown, that at an extremely strong waste of friction coefficient of clutch and respectively of brakes or at detecting a false motor factor out of which the gearbox speed factor is counted, the regular safety defaults are not sufficient to ensure the transmission capability of the clutch.
In German patent application DE 100 10 815, a technique for driving from load circuit of an automatic gearbox is described where during calculation of a pressure pattern for one during changing gear to the first, open clutch and a second, closing clutch a static engine factor, a dynamic engine factor, specific gear parameter and additionally a representing factor input of a ruling size are defined in a way that the value in a gear tolerance, including regulation, will become so definite that a target-flextime of the clutch will be at least approximately maintained. With the addition of a supplementary factor, obtained from the regulation, to the static engine factor, defined by driving, and to a dynamic engine factor, tolerance of electronics of automatic transmission, specific to a component, is known, by which a slip-time of the clutch can be stopped so that a theoretic slip-time is neither too long nor too short. Following is a foreseen adaptation of forward driving pressure of clutches, with which tolerance, strays, and low frequency modification of clutch friction coefficient and other parameters that influence shifting quality, can advantageously be balanced for the long-term and differential controller intervention reduces in the following shifts in a similar load.
The technique described in DE 100 10 815, however, limits itself to the phase of a switchgear during a loaded circuit and does not influence the clutch pressure-characteristic curve of the clutch outside the switching phase.
The task of the present invention is to provide a technique for driving of automatic transmission of a vehicle by establishing a characteristic curve of a clutch pressure for the state outside a gear change which will be thus improved. On the one hand, the efficiency of gearbox, in normal use, will improve and, on the other hand, will provide a sufficient control of the transmission capability in case of gearbox damage.
While the clutch pressure is applied, depending on gearbox input factor and a gear as a characteristic curve in an electronic driving unit, while a state outside a gearshift that depends on the real transmission capability of the clutch, is established, a very low safety default is selected which makes it possible to maintain the required pressure reserves and sufficiently improve the effectiveness of the gearbox.
In addition, according to the invention, the technique offers the advantage that the occurence of an insufficient transmission capability of the clutch and a clutch-slip outside gear-switches, which can lead to the damage or even to the clutch burning as well as result in gearbox failure, must be avoided.